In wireless communication system, particularly a cellular radio communication system, mobile devices operating on the system may wirelessly communicate with the communication network over a variety of air interface protocols. When wireless communication systems, and their associated mobile devices, operate under multiple air interface protocols, the devices and systems may be referred to respectively as hybrid mobile devices and hybrid communication systems. As an example of hybrid communication, a hybrid mobile device may use a first protocol for high speed data communications with the network, such as Internet browsing or e-mail exchange, and the hybrid mobile device may use a second protocol for voice calls and low speed data communications with the network, such as receiving and sending Short Message Service (SMS) messages.
A common aspect of some hybrid communication systems is that the hybrid mobile devices cannot operate over multiple air interface protocols simultaneously; the devices are limited to communicating over only one air interface protocol for any given time period and must switch between the protocols periodically. For example, while a hybrid mobile device is receiving high data rate communications over a first protocol, the hybrid device may have to periodically interrupt the transmission to switch over to a second protocol to check for incoming voice calls.
Typically a mobile device, whether a hybrid device or not, will check for incoming calls on a control channel that operates under the second protocol and that carries signaling messages transmitted from the network to the mobile devices. Most commonly, the control channel is a paging channel (PCH) that carries pages messages for the mobile devices. A mobile device will listen to the paging channel for pages addressed to the mobile device and then it may act on any pages it receives. For example, the mobile device may receive a page that a voice call is waiting to be connected and then the mobile device may act to set up the voice call on the network.
Paging channels, and the page messages carried on them, may carry a significant amount of information, including detailed network overhead information. Because so much information is carried on the paging channels, and because page messages for all the mobile devices on the network are typically carried sequentially in time over the paging channel, it may take a substantial amount of time for any given mobile device to check for its own pages. Additionally, and particularly if the page message is long, the mobile device may not receive the entire page message on its first attempt to listen to the message. When that occurs, the mobile device must wait until the page message is repeated on the paging channel in order to receive the entire contents of the page message.
Because the act of listening for page messages may take a significant amount of time, some wireless communication systems may employ a second control channel, frequently known as a quick paging channel (QPCH), which may use quick page messages to tell a mobile device that it should monitor the paging channel for a page message. Unless the mobile device receives a quick page message from the quick paging channel, it need not listen to the paging channel.
The quick paging channel carries significantly less information than the paging channel, and the quick pages carried by the quick paging channel can be listened to very quickly. Further, quick paging channels may frequently operate in a slotted mode, in which each mobile device is assigned a particular repeating time slot on the quick paging channel. Consequently, each mobile device need only listen to the quick paging channel during its assigned time slot, thereby reducing the time spent listening to the quick paging channel. (Though paging channels may also operate on a slotted basis, the assigned time slots are typically much longer and carry more information than the time slots assigned on a quick paging channel.) The net benefit of a quick paging control channel is that it reduces the amount of time the mobile device must spend listening to the network to see if it must take further action on the network.
This reduction in time is particularly useful to hybrid mobile devices, which must interrupt their communication under a first protocol in order to switch over to a second protocol to check for messages. The presence of a quick paging channel under the second protocol reduces the hybrid mobile device's time away from the first protocol.